Untersuchungen zum Keimgehalt pasteurisierter Konsummilch

High temperature short time pasteurized (HTST, n=268) and high temperature pasteurized (HTP,,,extended shelf life, n=16) drinking milk was purchased from retail shops (n=53) in middle Hessia (Germany) between January and August 2004. These samples were analysed at the day of the minimum storage life for total aerobic bacteria (at +30 °C and +21 °C, respectively) and coliforms. The median value for total bacteria at +30 °C and +21 °C was 2.0 x 10 3 cfu/ml and 2.3 x 10 3 cfu/ml, respectively. Total bacteria exceeded 3.0 x 10 4 cfu/ml (at +30 °C) or 5.0 x 10 4 cfu/ml (at +21 °C) in about 17 % of HTST samples, total bacteria exceeded 10 6 cfu /ml in about 7 % of HTST samples (maximum 3.7 x 10 7 cfu/ml). Total bacteria numbers were typical for a certain product in most cases, regardless of the place of purchase. Seasonal influences were minor, although the median value for total bacteria count was approx. two times higher in samples purchased in summer months, compared with samples from winter months. Coliform bacteria were detected in a total of 3 % of HTST samples (all positives had >10 2 coliforms/ml), with higher frequency in winter (6 %) than in summer (2 %). For HTP samples, only milk from one of five producers had detectable numbers of total bacteria (10 3 -10 6 cfu/ml), but all HTP samples were negative for coliforms. The results show that, although the majority of drinking milk was of excellent microbiological quality at the end of the minimum storage life, 17 % of all tested products had elevated numbers of total bacteria or inacceptable numbers of coliform bacteria.